The technology relies on the fact that quadriplegics and others retain control of their soft palates, which regulate breathing through the nose. Even people who are not able to breathe on their own can control the new device by blocking and releasing the flow of air forced through their noses by a pump.

The technology "may provide a host of viable solutions for the growing population of individuals who are severely disabled," the team wrote.

The device "is pretty ingenious in giving people who can't control their environment another way to do that," said Dr. Adam Stein, chairman of physical medicine and rehabilitation at North Shore-Long Island Jewish Health System in Great Neck, N.Y.

It would be particularly valuable for people who have locked-in syndrome, in which they can do little more than flutter an eyelid, he said. For many other patients, however, alternatives exist, including controlling devices through a breathing tube or with the tongue.

The mechanism is relatively simple. Small tubes in the nose monitor sniffs and exhalations, enabling the user to control a computer. To control a wheelchair, for example, two short sniffs signal a forward move, and two short exhalations signal backward. An exhale followed by a sniff signals left, and a sniff followed by an exhale signals right. Similar protocols can move a cursor on a computer screen for writing.

Neurobiologist Noam Sobel of the Weizmann Institute of Science in Tel Aviv and his colleagues initially studied the device in 96 healthy people, demonstrating that they could control the movement of a cursor with it as easily as they could with a joystick or mouse. About 1 in 4 could not work the device properly, however.

The researchers then tested the device with a 51-year-old woman who had suffered a stroke seven months earlier; she could not move her limbs and was unable to control her blinking, the most common means of communication in such patients. After training her to control her breaths, they presented her with a writing device that she began using immediately, "initially answering questions, and after a few days [she] generated her first post-stroke meaningful self-initiated communication that entailed a profound personal message to her family."

They next tested the device with a 42-year-old man who had been locked in for 18 years after a car accident. He had attempted to use an eye-tracker to communicate, but stopped because he "did not like it." The new device, he said, was "more comfortable and more easy to use."

The device did not work on the third patient, however, a 64-year-old man who had suffered a stroke four years earlier. The man was severely depressed, and the researchers could not determine "whether this failure reflected a genuine inability or rather disinterest."

The team installed the device on a wheelchair and demonstrated, first with healthy people, then with disabled, that it could be used to navigate a 150-foot obstacle course including sharp turns.

Overall, the device has now been tested successfully in 15 severely disabled patients. The Weizmann Institute has filed for a patent on the technology used in the device and hopes to find a marketing partner.